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Chapter 15. Storage

The multipath utility can now save data between prioritizer calls

This feature has been implemented in the asymmetric logical unit access (ALUA) prioritizer, and reduces the number of commands sent to the target array. As a result, target arrays are no longer overloaded with commands if there is a large number of paths. (BZ#1081395)

Asynchronous checkers can use the multipath checker_timeout option

Asynchronous checkers now use the checker_timeout option in the multipath.conf file to determine when to stop waiting for a response from the array and fail the non-responsive path. This behavior for asynchronous checkers can be configured in the same way as for synchronous checkers. (BZ#1153704)

nfsidmap -d option added

The nfsidmap -d option has been added to display the system's effective NFSv4 domain name on stdout. (BZ#948680)

Configurable connection timeout for mounted CIFS shares

Idling CIFS clients send an echo call every 60 seconds. The echo interval is hard-coded, and is used to calculate the timeout value for an unreachable server. This timeout value is usually set to (2 * echo interval) + 17 seconds. With this feature, users can change the echo interval setting, which enables them to change the timeout interval for unresponsive servers. To change the echo interval, use the echo_interval=n mount option, where n is the echo interval in seconds. (BZ#1234960)

Support for device-mapper statistics facility (dmstats)

The Red Hat Enterprise Linux 6.8 release supports a device-mapper statistics facility, the dmstats program. The dmstats program displays and manages I/O statistics for user-defined regions of devices that use the device-mapper driver. The dmstats program provides a similar functionality to the iostats program, but at levels of finer granularity than a whole device. For information on the dmstats program, see the dmstats(8) man page. (BZ#1267664)

Support for raw format mode in multipathd formatted output commands

The multipathd formatted ouput commands now offer a raw format mode that removes the headers and additional padding between fields. Support for additional format wildcards has been added as well. Raw format mode makes it easer to collect and parse information about multipath devices, particularly for use in scripting. For information on raw format mode, see the DM Multipath Guide. (BZ#1145442)